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我尝试保存缓存文件(例如现在文件)我CacheOperator类时发送广播意图:错误试图保存缓存文件
public class CacheOperator {
Context c;
public void saveSth() {
String FILENAME = "hello_file";
String string = "hello world!";
FileOutputStream fos = null;
try {
fos = c.openFileOutput(FILENAME, Context.MODE_PRIVATE);
fos.write(string.getBytes());
fos.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
我overrided使用默认替代所有上下文方法+回车键。
当代码获取到托运的地方,应用程序停止,有例外:
E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{pl.app.partyme/pl.app.partyme.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2085)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2110)
at android.app.ActivityThread.access$600(ActivityThread.java:138)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1205)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4940)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:798)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:565)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at pl.app.partyme.tools.CacheOperator.saveSth(CacheOperator.java:49)
at pl.app.partyme.MainActivity.onCreate(MainActivity.java:29)
at android.app.Activity.performCreate(Activity.java:5255)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1082)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2049)
我应该先创建这个文件somewhow还是什么?
我没有看到上下文℃;初始化/分配到任何地方 – dymmeh
@dymmeh你能帮我吗? – pawel
添加了一个应该帮助的答案。 – dymmeh